This is a program of research on two kinds of basic processes in psychological development: (1) biological factors and (2) the development of cognitive controls over action. In the first category, individual projects within the program deal with: (a) changes in brain function, occurring during infancy, which are involved in the early development of perception; (b) the relation of biochemical factors, present at birth, to stable individual differences in social-emotional behavior; and (c) certain thought processes involved in reasoning -- which, it appears may not change with age and experience and hence may prove to be (to some degree) "built in" to human functioning. In the second category, individual projects will be concerned with: (a) the role of cognitive strategies in children's self-regulation, and how these change with growth and experience; (b) the conditions under which external incentives have positive or negative effects on behavior, and the cognitive processes which determine these effects; and (c) the linkages between moral reasoning and children's choices of alternative courses of action.